The invention is in the field of fluid valves, and more particularly it is concerned with a temperature operated gas valve wherein a plug of material is melted to open the valve. In a specific context, the invention is related to laser gas fill systems wherein supplementary gas must be admitted into a gas laser tube a number of times during the life of the laser.
Gas lasers such as argon lasers have a plasma tube which must be filled with argon gas prior to startup of the laser. As described in U.S. Pat. No. 4,683,575, assigned to the assignee of the present invention, the gas fill systems for these lasers have often included rubber seals or other rubber-like valve closure components which could not be baked at a high temperature. As a result, two separate baking operations were required to clean the different portions of the laser assembly, one at a high temperature and another at a lower temperature. It would be desirable to clean all components, including the gas fill system components, at the higher temperature.
The disclosure of U.S. Pat. No. 4,683,575 is hereby incorporated by reference into this application.
In the gas laser and in other environments, mechanical valves are sometimes impractical or inefficient or too costly. There has often been a need for an alternative to a mechanical valve for controlling the movement of gas from a higher pressure region to a lower pressure region, with the capability of remote electrical operation of the valve.
Valve constructions satisfying these needs are among the objects of the present invention described below.